The present invention relates to the field of optical waveguides and, more particularly, to the materials used to construct optical waveguides.
Current communications networks throughout the world have embraced the use of optical fiber waveguide technology to provide a conduit of transmission components for voice, video, and data signals. Optical networks offer far greater bandwidth and reliability than do conventional electronic networks. As a consequence, current research efforts have been directed to expanding the capabilities of optical waveguide technology at reduced cost to aid in the acceleration of the conversion of the present electrical communications networks to optical communications networks.
These optical communications networks are comprised of many different components. These include optical fiber cable, switches, attenuators, couplers, and many more such devices. Typically, these devices are comprised of a core surrounded by a cladding material. Both the materials used for the core and the cladding include silica or doped silica as well as many other similar materials. These materials are employed because they have a desirable index of refraction and as well as other properties which facilitate their use.
Of ten times it is desirable to create specific effects on the propagation of the optical signal transmitted through these devices. For example, one such effect is to either attenuate or interrupt an optical signal. Consequently, there is a need for new optical structures which will facilitate the attenuation and interruption of an optical signal in an optical waveguide.
The present invention entails an optical attenuator having a core which is covered by a cladding material with a section of polymer cladding of an identifiable length. The polymer cladding has an index of refraction that varies with temperature. A thermal device such as a thermoelectric heater or cooler is placed adjacent to the polymer cladding to control the temperature of the cladding. The index of refraction of the polymer cladding is manipulated by changing its temperature by supplying power to the thermal device. The index of refraction of the polymer cladding will range from values below and above the index of refraction of the core material. A light wave transmitted through the core will experience a degree of attenuation due to leakage into the polymer cladding material when the index of refraction of the polymer cladding is equal to or greater than the index of refraction of the core. The light wave may be partially or entirely attenuated.
The present invention may also be viewed as a method for attenuating an optical signal in a waveguide comprising the steps of transmitting an optical signal having an initial power strength through an optical attenuator having a section of polymer cladding of identifiable length, and determining a desired optical signal strength at the output of the optical attenuator. Finally, the step of controlling the temperature of the polymer cladding to attenuate the optical signal to the desired optical signal strength is performed.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention, as defined by the claims.